// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/json/json_writer.h"

#include <stdint.h>

#include <cmath>
#include <limits>

#include "base/json/string_escape.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
#include "build/build_config.h"

namespace base {

#if defined(OS_WIN)
const char kPrettyPrintLineEnding[] = "\r\n";
#else
const char kPrettyPrintLineEnding[] = "\n";
#endif

// static
bool JSONWriter::Write(const Value& node, std::string* json)
{
    return WriteWithOptions(node, 0, json);
}

// static
bool JSONWriter::WriteWithOptions(const Value& node,
    int options,
    std::string* json)
{
    json->clear();
    // Is there a better way to estimate the size of the output?
    json->reserve(1024);

    JSONWriter writer(options, json);
    bool result = writer.BuildJSONString(node, 0U);

    if (options & OPTIONS_PRETTY_PRINT)
        json->append(kPrettyPrintLineEnding);

    return result;
}

JSONWriter::JSONWriter(int options, std::string* json)
    : omit_binary_values_((options & OPTIONS_OMIT_BINARY_VALUES) != 0)
    , omit_double_type_preservation_(
          (options & OPTIONS_OMIT_DOUBLE_TYPE_PRESERVATION) != 0)
    , pretty_print_((options & OPTIONS_PRETTY_PRINT) != 0)
    , json_string_(json)
{
    DCHECK(json);
}

bool JSONWriter::BuildJSONString(const Value& node, size_t depth)
{
    switch (node.GetType()) {
    case Value::Type::NONE: {
        json_string_->append("null");
        return true;
    }

    case Value::Type::BOOLEAN: {
        bool value;
        bool result = node.GetAsBoolean(&value);
        DCHECK(result);
        json_string_->append(value ? "true" : "false");
        return result;
    }

    case Value::Type::INTEGER: {
        int value;
        bool result = node.GetAsInteger(&value);
        DCHECK(result);
        json_string_->append(IntToString(value));
        return result;
    }

    case Value::Type::DOUBLE: {
        double value;
        bool result = node.GetAsDouble(&value);
        DCHECK(result);
        if (omit_double_type_preservation_ && value <= std::numeric_limits<int64_t>::max() && value >= std::numeric_limits<int64_t>::min() && std::floor(value) == value) {
            json_string_->append(Int64ToString(static_cast<int64_t>(value)));
            return result;
        }
        std::string real = DoubleToString(value);
        // Ensure that the number has a .0 if there's no decimal or 'e'.  This
        // makes sure that when we read the JSON back, it's interpreted as a
        // real rather than an int.
        if (real.find('.') == std::string::npos && real.find('e') == std::string::npos && real.find('E') == std::string::npos) {
            real.append(".0");
        }
        // The JSON spec requires that non-integer values in the range (-1,1)
        // have a zero before the decimal point - ".52" is not valid, "0.52" is.
        if (real[0] == '.') {
            real.insert(static_cast<size_t>(0), static_cast<size_t>(1), '0');
        } else if (real.length() > 1 && real[0] == '-' && real[1] == '.') {
            // "-.1" bad "-0.1" good
            real.insert(static_cast<size_t>(1), static_cast<size_t>(1), '0');
        }
        json_string_->append(real);
        return result;
    }

    case Value::Type::STRING: {
        std::string value;
        bool result = node.GetAsString(&value);
        DCHECK(result);
        EscapeJSONString(value, true, json_string_);
        return result;
    }

    case Value::Type::LIST: {
        json_string_->push_back('[');
        if (pretty_print_)
            json_string_->push_back(' ');

        const ListValue* list = NULL;
        bool first_value_has_been_output = false;
        bool result = node.GetAsList(&list);
        DCHECK(result);
        for (const auto& value : *list) {
            if (omit_binary_values_ && value->GetType() == Value::Type::BINARY)
                continue;

            if (first_value_has_been_output) {
                json_string_->push_back(',');
                if (pretty_print_)
                    json_string_->push_back(' ');
            }

            if (!BuildJSONString(*value, depth))
                result = false;

            first_value_has_been_output = true;
        }

        if (pretty_print_)
            json_string_->push_back(' ');
        json_string_->push_back(']');
        return result;
    }

    case Value::Type::DICTIONARY: {
        json_string_->push_back('{');
        if (pretty_print_)
            json_string_->append(kPrettyPrintLineEnding);

        const DictionaryValue* dict = NULL;
        bool first_value_has_been_output = false;
        bool result = node.GetAsDictionary(&dict);
        DCHECK(result);
        for (DictionaryValue::Iterator itr(*dict); !itr.IsAtEnd();
             itr.Advance()) {
            if (omit_binary_values_ && itr.value().GetType() == Value::Type::BINARY) {
                continue;
            }

            if (first_value_has_been_output) {
                json_string_->push_back(',');
                if (pretty_print_)
                    json_string_->append(kPrettyPrintLineEnding);
            }

            if (pretty_print_)
                IndentLine(depth + 1U);

            EscapeJSONString(itr.key(), true, json_string_);
            json_string_->push_back(':');
            if (pretty_print_)
                json_string_->push_back(' ');

            if (!BuildJSONString(itr.value(), depth + 1U))
                result = false;

            first_value_has_been_output = true;
        }

        if (pretty_print_) {
            json_string_->append(kPrettyPrintLineEnding);
            IndentLine(depth);
        }

        json_string_->push_back('}');
        return result;
    }

    case Value::Type::BINARY:
        // Successful only if we're allowed to omit it.
        DLOG_IF(ERROR, !omit_binary_values_) << "Cannot serialize binary value.";
        return omit_binary_values_;
    }
    NOTREACHED();
    return false;
}

void JSONWriter::IndentLine(size_t depth)
{
    json_string_->append(depth * 3U, ' ');
}

} // namespace base
